Treatment of a solid tumor using engineered drug-resistant immunocompetent cells and cytotoxic chemotherapy.

Multimodal therapy approaches, such as combining chemotherapy agents with cellular immunotherapy, suffers from potential drug-mediated toxicity to immune effector cells. Overcoming such toxic effects of anticancer cellular products is a potential critical barrier to the development of combined therapeutic approaches. We are evaluating an anticancer strategy that focuses on overcoming such a barrier by genetically engineering drug-resistant variants of immunocompetent cells, thereby allowing for the coadministration of cellular therapy with cytotoxic chemotherapy, a method we refer to as drug-resistant immunotherapy (DRI). The strategy relies on the use of cDNA sequences that confer drug resistance and recombinant lentiviral vectors to transfer nucleic acid sequences into immunocompetent cells. In the present study, we evaluated a DRI-based strategy that incorporates the immunocompetent cell line NK-92, which has intrinsic antitumor properties, genetically engineered to be resistant to both temozolomide and trimetrexate. These immune effector cells efficiently lysed neuroblastoma cell lines, which we show are also sensitive to both chemotherapy agents. The antitumor efficacy of the DRI strategy was demonstrated in vivo, whereby neuroblastoma-bearing NOD/SCID/γ-chain knockout (NSG) mice treated with dual drug-resistant NK-92 cell therapy followed by dual cytotoxic chemotherapy showed tumor regression and significantly enhanced survival compared with animals receiving either nonengineered cell-based therapy and chemotherapy, immunotherapy alone, or chemotherapy alone. These data show there is a benefit to using drug-resistant cellular therapy when combined with cytotoxic chemotherapy approaches.

S9511: a Southwest Oncology Group phase II study of trimetrexate, 5-fluorouracil, and leucovorin in unresectable or metastatic adenocarcinoma of the stomach.

OBJECTIVE: The primary objective of this trial was to evaluate the response rate for trimetrexate in conjunction with 5-FU and leucovorin (LV) (= TFL) in the treatment of advanced gastric cancer in a phase II, cooperative group setting. METHODS: Patients with locally advanced, unresectable, or metastatic adenocarcinoma of the stomach received trimetrexate 110 mg/m IV over 60 minutes day 1, followed by 5-FU 500 mg/m IV bolus and LV 200 mg/m IV over 60 minutes day 2, followed by oral LV 15 mg every 6 hours x 7 doses, all weekly for 6 weeks followed by 2 weeks of rest, continued until progression. RESULTS: Characteristics for 37 eligible patients: median age 63 (range: 23-83); male/female: 69% of 31%; performance status 0/1/2 15/20/1. The confirmed response rate was 19%, and median overall survival was 6 months. Two patients died as a result of therapy, 1 because of infection without significant neutropenia, and 1 due to perforation of a responding gastric lesion. Seventy-two percent experienced grades 3 and 4 toxicity, most commonly diarrhea, fatigue, and lymphopenia. CONCLUSIONS: This regimen achieves response rates comparable to other 5-FU-based regimens, when used in treatment of incurable gastric cancer. Toxicity appears manageable.

Raloxifene and selective cell cycle specific agents: a case for the inclusion of raloxifene in current breast cancer treatment therapies.

BACKGROUND: Breast cancer patients are at increased risk of osteoporosis. Contributing factors include age and/or chemotherapy. The selective estrogen modulator, raloxifene (RAL), effective in the prevention of breast cancer and approved for the treatment and prevention of osteoporosis, may prove beneficial in current breast cancer treatment modules. The purpose of this study was to evaluate RAL in combination with 5-fluorouracil (5-FU) and trimetrexate (TMX) to determine the most effective sequence in which to administer these cell cycle specific agents while taking into consideration the cellular mechanism of action. The goal was to maintain cytotoxicity to breast cancer cells and capitalize on the selective estrogen receptor modulatory effects of RAL. MATERIALS AND METHODS: MCF-7 cells were exposed to (i) TMX, 5-FU or RAL alone, or (ii) RAL 24 h prior to 5-FU followed 2 h later by TMX, or (iii) 5-FU 2 h prior to TMX followed 24 h later by RAL. The cell viability was determined using the Quick Cell Proliferation Assay. RESULTS: The growth rate of MCF- 7 cells exposed to early RAL was 68.25 +/- 4.11% that of the control, however, late RAL exposure produced a growth of 34.75 +/- 4.79% that of the control. Late RAL maintained the cytotoxicity of the regimen. The findings were further supported by cell flow cytometry and Western blot analysis data. CONCLUSION: RAL given prior to 5-FU/TMX significantly compromised cytotoxicity to breast cancer cells.

The protection against trimetrexate cytotoxicity in human bone marrow by sequence-dependent administration of raloxifene, 5-fluorouracil/trimetrexate.

BACKGROUND: Currently, one of the most effective strategies for the treatment and prevention of breast cancer is the use of drugs that block estrogen action in the breast. The success of the first clinically relevant selective estrogen receptor modulator (SERM), tamoxifen, provided the foundation for further testing of this drug to reduce breast cancer incidence in high-risk women. However, the negative effects associated with the long-term use of tanrhoxifen have initiated the search for compounds that are more effective but less toxic. The discovery of raloxifene (RAL), which functions as a potent antiestrogen in the breast but an estrogen receptor (ER) agonist in the bone and cardiovascular system with very little uterotropic activity, provided an alternative strategy to the targeted use of tamoxifen. The aim of this study was to evaluate RAL in combination with 5-fluorouracil (5-FU)/trimetrexate (TMX) to determine the most effective regimes and cellular mechanism of action to mitigate trimetrexate cytotoxicity in human bone marrow cells. MATERIALS AND METHODS: The cell viability was performed using the Quick Cell Proliferation Assay by exposing the cells to TMX, 5-FU and RAL alone; RAL 24 h prior to 5-FU followed 2 h by TMX, and 5-FU 2 h prior to TMX followed 24 h by RAL determined the sequence-dependent interaction between TMX, 5-FU and RAL on the proliferation. RESULTS: The growth rate in MCF-7 in late RAL was 34.75 +/- 4.79% of the control, whereas in bone marrow the same drug combination exhibits a significant protection against TMX cytotoxicity with late RAL yielding 51.25 +/- 4.43% of the control. The findings were also supported by Cell flow cytometry and Western blot analysis. CONCLUSION: Sequence-dependent administration of RAL in combination with 5-FU/TMX can act against TMX toxicity in human bone marrow, while not affecting the maximum inhibitory effect of TMX in breast cancer.

A phase I/II study of trimetrexate and capecitabine in patients with advanced refractory colorectal cancer.

OBJECTIVE: We tested the hypothesis that the combination of trimetrexate (TMTX) and capecitabine (CAP) would be active in patients with previously treated metastatic colorectal cancer (CRC). Because the optimum dose of this combination was unknown, we used a phase I/II design. METHODS: In the phase I cohort, patients received 110 mg/m2 TMTX intravenously weekly x6 and CAP starting at 750 mg/m2 orally twice daily from days 2 to 15 and 23 to 36 (one cycle). Cycles were repeated every 8 weeks. The phase II doses were 110 mg/m2 TMTX and 1000 mg/m2 CAP orally twice daily. RESULTS: Thirty-two patients were entered. All patients had prior 5-fluorouracil therapy and 94% had prior exposure to irinotecan. Grade 3/4 toxicities included abdominal pain in 4 patients (12.5%) and vomiting in 3 patients (9.4%). Twenty-seven patients were evaluable for response: one patient each had a complete response and a partial response for an overall response rate of 7.4%. The median time to progression was 3.3 months (95% confidence interval [CI], 1.6-3.7 months) and the median overall survival was 5.9 months (95% CI, 5.2-10.2 months). CONCLUSIONS: The combination of TMTX and CAP is well tolerated. However, recent studies have shown more active regimens in the second- and third-line metastatic setting.

Double modulation of 5-fluorouracil by trimetrexate and leucovorin in patients with advanced colorectal carcinoma.

The purpose of this report is to evaluate the efficacy and toxicity (Tx) of a double modulation of 5-fluorouracil (5-FU) by trimetrexate (TMTX) and leucovorin (LV) in patients with advanced recurrent (inoperable) or metastatic colorectal cancer (ACC). Between December 1997 and August 2000, 36 patients were entered in this phase II study. Median age was 61 years, and 18 patients (50%) were female. Median performance status was 0 (range: 0-1), whereas primary tumor location was colon in 21 patients (58%) and rectum in 15 patients (42%). The number of metastatic sites was 1:29 patients (81%); 2:6 patients (17%) and 3:1 patient (3%). Hepatic involvement was observed in 33 patients (92%). Treatment consisted of TMTX 110 mg/m2 IV over 1 hour at hour (H) 0; LV 50 mg/m2 IV over 2 hours IV infusion starting at H 18; and 5-FU 900 mg/m2 IV bolus at H 20. LV (rescue) 15 mg/m2 orally was administered every 6 hours (total 6 doses) beginning at H 24. Cycles were repeated every 2 weeks until progressive disease (PD) or severe Tx. Thirty-four patients are assessable for response (R) (two patients refused further treatment after the first course of therapy), whereas all patients were assessable for Tx. Complete response: 1 patient (3%); partial response: 4 patients (12%), with an overall objective response rate of 15% (95% CI, 1%-25%); no change: 12 patients (35%); and progressive disease: 17 patients (50%). The median time to treatment failure was 4 months and median survival was 11 months. Tx was within acceptable limits. The dose-limiting side effect was mucositis. Eight episodes of grade II or III stomatitis were observed and were responsible for dosage modifications of TMTX and 5-FU. Leukopenia was observed in 16 patients (44%); neutropenia was registered in 19 patients (53%); anemia was seen in 18 patients (50%); emesis in 22 patients (61%); and dermatitis in 3 patients (8%). There were no therapy-related deaths. The double modulation of 5-FU by TMTX and LV showed modest antitumoral activity with mild to moderate Tx.

Large diversity in transport-mediated methotrexate resistance in human leukemia cell line CCRF-CEM established in a high concentration of leucovorin.

To elucidate the mechanism(s) of methotrexate (MTX) resistance as a possible reason underlying treatment failure in high-dose MTX regimens combined with leucovorin (LV) rescue, we established MTX-resistant human T-cell leukemia cell line CCRF-CEM cells in the presence of excess LV, and characterized their properties. Continuous exposure of the cells to escalating concentrations of MTX up to 20 microM in the presence of 1000 nM LV resulted in establishment of three MTX-resistant sublines with a wide disparity of resistance degree over a 4 logarithmic range (approximately 40-, 900- and 44,000-fold, respectively). Transmembrane transport of MTX in these sublines was diminished to 52%, 35% and 12%, respectively. Intracellular retention of MTX in these sublines was not different from that of the parent cells. A cell growth study in various concentrations of LV showed that cells with higher resistance to MTX required more LV for optimal growth. In parallel with the resistance levels, there was an increase in mRNA expression of dihydrofolate reductase gene and a decrease in that of thymidylate synthase gene, but no change in that of reduced folate carrier (RFC1) gene, as assessed by northern blot analysis. Sequencing of the RFC1 gene in all 3 sublines revealed a point mutation in codon 47 (TCC-->TTC) resulting in substitution of Phe for Ser residue, and additional deletion of CTG of codon 112 in the subline with the highest resistance. In summary, MTX exposure to CCRF-CEM cells in the presence of 1000 nM LV resulted in the establishment of heterogeneous cell populations with a wide range of transport-mediated MTX resistance, which was associated with differential alterations of RFC gene. These cell lines may serve as models for investigation of the molecular mechanism(s) underlying refractory tumors in high-dose MTX regimens with LV rescue.

Trimetrexate inhibits progression of the murine 32Dp210 model of chronic myeloid leukemia in animals expressing drug-resistant dihydrofolate reductase.

Expression of drug-resistant forms of dihydrofolate reductase (DHFR) in hematopoietic cells confers substantial resistance of animals to antifolate administration. In this study, we tested whether the chemoprotection conferred by expression of the tyrosine-22 variant DHFR could be used for more effective therapy of the 32Dp210 murine model of chronic myeloid leukemia (CML). Administration of the maximum tolerated dose of trimetrexate (TMTX) with the nucleoside transport inhibitor prodrug nitrobenzylmercaptopurine ribose-5'-monophosphate (NBMPR-P) inhibited 32Dp210 tumor progression in mice engrafted with transgenic tyrosine-22 DHFR marrow and improved survival of tumor-bearing animals as long as drug administration was continued. NBMPR-P coadministration was necessary for maximal tumor inhibition, as administration of TMTX alone delayed but did not prevent tumor progression. The chemoprotection afforded by engraftment with transgenic tyrosine-22 DHFR marrow was necessary for effective chemotherapy, as normal mice lacking transgenic marrow could not tolerate the higher TMTX dose (60 mg/kg/day) administered to mice with transgenic marrow, and the decreased dose of TMTX with NBMPR-P tolerated by normal tumor-bearing animals did not inhibit tumor progression or improve animal survival. We conclude that TMTX with NBMPR-P inhibits tumor progression in the 32Dp210 model of CML in animals engrafted with drug-resistant tyrosine-22 DHFR transgenic marrow, and that based on this model the introduction of a drug-resistant DHFR gene into marrow combined with TMTX and NBMPR-P administration may provide an effective treatment for CML.

Phase II clinical trial of 5-fluorouracil, trimetrexate, and leucovorin (NFL) in patients with advanced pancreatic cancer.

BACKGROUND: Advanced pancreatic cancer has limited treatment options. 5-fluorouracil (5-FU) is frequently used in the treatment of pancreatic cancer. Preclinical studies suggest synergism between trimetrexate (TMTX),5-FU, and leucovorin (NFL). AIM: We conducted a phase II trial to evaluate the activity and safety of NFL in pancreatic cancer. METHOD: Eligible patients (n = 21) with untreated advanced pancreatic cancer were treated with 110 mg/m2 intravenous (IV) THTX on day 1 and 200 mg/m2 IV leucovorin prior to 500 mg/m2 IV 5-FU on day 2. Oral leucovorin (15 mg every 6 h for seven doses) started intravenous 24 h later. RESULTS: Treatment was administered for 6 wk followed by a 2-wk rest period. Response was evaluated every 8 wk. All patients were evaluable for response and toxicity. Most patients (80%) had distant metastases. Forty-five cycles of chemotherapy were administered. The most common serious toxicities were Grade 3 diarrhea (23.8%) and nausea and vomiting (14.2%). The response rate was 4.1% (95% CI, 0-23%), median survival was 6.8 mo, and 1-yr survival was 19%. CONCLUSION: Treatment with NFL is well-tolerated in patients with advanced pancreatic cancer. The median survival and 1-yr survival in these patients with poor prognosis compares favorably with other treatment options.

Low-dose trimetrexate glucuronate and protracted 5-fluorouracil infusion in previously untreated patients with advanced pancreatic cancer.

BACKGROUND: 5-Fluorouracil (5-FU)-based regimens have not been shown to prolong survival or provide clinical benefit in patients with advanced pancreatic cancer. The purpose of this study was to determine the tolerability of protracted venous infusion (PVI) of 5-FU, modulated by a low dose of the synthetic antifolate trimetrexate, in patients with advanced pancreatic cancer. PATIENTS AND METHODS: Twenty-three chemotherapy-naïve patients were evaluated. Patients were enrolled in four consecutive cohorts in which the weekly dose of trimetrexate was escalated in 10 mg/m2 increments, from 20 to 50 mg/m2. PVI 5-FU was administered at a fixed dose of 225 mg/m2/day. Treatment was administered for 6 successive weeks, every 8 weeks. RESULTS: Twenty-two patients were assessable. The maximum tolerated dose of trimetrexate was 40 mg/m2. The most common grade 3 and 4 toxicity was diarrhea. There were no treatment-related deaths. Preliminary analysis of activity revealed a response rate of 9%, with 41% of the patients having stable disease for a median duration of 3.8 months. The median survival for the entire group was 6.9 months (range 1-29 months). A clinical benefit response was experienced by 27.2% of patients. CONCLUSIONS: Low-dose trimetrexate can be safely administered in combination with PVI 5-FU. This treatment is well tolerated and is associated with palliative activity in advanced pancreatic cancer.

Trimetrexate in relapsed T-cell lymphoma with skin involvement.

PURPOSE: Methotrexate (MTX) is active against lymphomas, but transport or polyglutamylation mutations confer MTX resistance. Because trimetrexate (TMTX) enters cells by passive diffusion and is not polyglutamylated, its activity in relapsed T-cell lymphoma was investigated. PATIENTS AND METHODS: Eligible patients had histologically confirmed relapsed T-cell lymphoma involving the skin, had received more than one previous regimen, were older than 16 years, had normal organ function, and had no CNS disease or serious infections, including human immunodeficiency virus. TMTX (200 mg/m(2)) was given intravenously every 14 days without topical or systemic corticosteroids. Patients who responded received up to 12 doses. RESULTS: Twenty patients were assessable for response. Median age was 59 years (range, 45 to 87 years); 13 patients were men. Three patients had anaplastic large-cell lymphoma, 15 had mycosis fungoides or Sézary syndrome (14 with large-cell transformation), and two had peripheral T-cell lymphoma. Serum lactate dehydrogenase was high in 35%, and beta-2 microglobulin was more than 3.0 mg/L in 35% of patients. The median number of previous regimens was three (range, two to 15) and included MTX in five patients. Disease was refractory to the regimen immediately preceding TMTX in 85% of patients. Responses were complete in one and partial in eight patients (overall response rate, 45%). Two of five patients previously treated with MTX responded. Grade 3 or 4 mucositis was observed after 4%, infection after 3%, neutropenic fever after 6%, neutrophils less than 100/microL after 4%, and platelets less than 10,000/microL after 3% of TMTX doses. CONCLUSION: TMTX is active with acceptable toxicity in this population and merits further investigation.

A meta-analysis of salvage therapy for Pneumocystis carinii pneumonia.

OBJECTIVE: To determine the relative efficacies of alternative antipneumocystis agents in human immunodeficiency virus (HIV)-infected patients with Pneumocystis carinii pneumonia unresponsive to primary drug treatment with a combination product of trimethoprim and sulfamethoxazole or parenteral pentamidine. METHODS: Meta-analysis of 27 published clinical drug trials, case series, and case reports involving P carinii pneumonia. Data extracted included underlying disease, primary antipneumocystis treatment, days of failed primary treatment, salvage regimen, use of systemic corticosteroids and antiretroviral drugs, and clinical outcome. RESULTS: In 497 patients with microbiologically confirmed P carinii pneumonia (456 with HIV or acquired immunodeficiency syndrome), initial antipneumocystis treatment failed and they therefore required alternative drug therapy. Failed regimens included trimethoprim-sulfamethoxazole (160 patients), intravenous pentamidine (63 patients), trimethoprim-sulfamethoxazole and/or pentamidine (258 patients), aerosolized pentamidine (6 patients), atovaquone (3 patients), dapsone (3 patients), a combination product of trimethoprim and dapsone (2 patients), and trimethoprim-sulfamethoxazole followed by a combination of clindamycin and primaquine phosphate (2 patients). Efficacies of salvage regimens were as follows: clindamycin-primaquine (42 to 44 [88%-92%] of 48 patients; P<10(-8)), atovaquone (4 [80%] of 5), eflornithine hydrochloride (40 [57%] of 70; P<.01), trimethoprim-sulfamethoxazole (27 [53%] of 51; P<.08), pentamidine (64 [39%] of 164), and trimetrexate (47 [30%] of 159). CONCLUSION: The combination of clindamycin plus primaquine appears to be the most effective alternative treatment for patients with P carinii pneumonia who are unresponsive to conventional antipneumocystis agents.

Implications for improved high-dose methotrexate therapeutic effects in cultured human breast cancer and bone marrow cells.

The cytotoxicity of high-dose methotrexate (MTX), 10 and 100 microM, and 5-fluorouracil (5-FU) combinations is independent of sequence in human MDA-MB-436 breast carcinoma cells. The growth inhibitory effects of 10 and 100 microM MTX are 22.54+/-1.56% and 16.20+/-0.74%, respectively, of the control rate. When the MTX and 5-FU concentrations are 10 microM, antiproliferative effects of MTX 2 hr before 5-FU (MTX/5-FU) and 5-FU 2 h before MTX (5-FU/MTX) are 25.17+/-1.23% and 25.60+/-1.28% of the control rate, respectively. The percentage of control rates for 5-FU alone is 94.89+/-1.35%. The growth rates of MDA-MB-436 cells in 100 microM MTX and 10 microM 5-FU are 15.19+/-0.62% (MTX/5-FU) and 16.53+/-0.85% (5-FU/MTX) of the control rate. The growth of cancer cells in the presence of 5-FU alone is 93.82+/-1.69% of the control rate. A comparison of the cell-killing effects of MTX and the nonpolyglutamable antifolate trimetrexate (TMQ) alone and in combination with 5-FU was performed to indirectly explore the role of polyglutamylation in breast cancer and bone marrow cells. The comparisons were made in equitoxic concentrations (10 microM) of MTX and TMQ and the time of exposure was the same. The inhibitory effects of TMQ, TMQ/5-FU, and 5-FU/TMQ in breast cancer cells were identical, but significantly less than MTX, MTX/5-FU, and 5-FU/MTX. The interaction between TMQ and MTX, TMQ/5-FU and MTX/5-FU, and 5-FU/TMQ and 5-FU/MTX was quantitatively similar in bone marrow. (Significant protection occurred in bone marrow cells exposed to 5-FU/TMQ and 5-FU/MTX.) Because the effects of 5-FU/MTX and 5-FU/TMQ on bone marrow were the same, it is unlikely that polyglutamylation plays a significant role in the protective effects of 5-FU. However, the greater inhibitory effect of MTX or MTX and 5-FU combinations, when compared with TMQ or TMQ and 5-FU, suggests that polyglutamylation of MTX may contribute to the cytotoxicity of this antifolate to breast cancer cells. Hence, these studies suggest that a priming and nontoxic dose of 5-FU before high-dose MTX sustains MTX cytotoxicity in breast cancer and protects against MTX toxicity to bone marrow progenitor cells.

Sequential trimetrexate, 5-fluorouracil and folinic acid are effective and well tolerated in metastatic colorectal carcinoma. The phase II study group of the AIO.

Trimetrexate (TMTX) is a new antifolate which avoids competition for cellular uptake with folinic acid (FA). A regimen of sequential TMTX, FA and 5-fluorouracil (5-FU) has shown efficacy in patients with colorectal cancer. Therefore, we treated 34 previously untreated patients with metastatic colorectal cancer with a weekly chemotherapy regimen consisting of 110 mg/m(2) of TMTX intravenously, then 24 h later 200 mg/m(2) of FA (i.v.) and 500 mg/m(2) of 5-FU (i. v.). Thereafter, 7 doses of oral FA (15 mg) were given at 6-hourly intervals. A treatment cycle consisted of 6 weeks of treatment, then 2 weeks of rest. All patients were treated as outpatients unless complications arose. Thirty-three patients were assessable for tumor response, and all 34 patients were assessable for toxicity. Twelve patients (36%; 95% confidence interval: 25-49%) achieved a partial response. The median duration of response was 8.5 months, and median survival was 14 months. The most common toxicity was diarrhea of grade 3/4, observed in 22% of treatment cycles; this decreased to 8% with early loperamide treatment. Hematologic toxicity was mild. The sequential administration of TMTX, FA and 5-FU is an active regimen in the first-line treatment of metastatic colorectal cancer and warrants further studies.

Where do we stand with 5-fluorouracil?

For nearly four decades, 5-fluorouracil (5-FU) has been the mainstay of treatment for colorectal cancer. Due to the lack of other agents with significant activity, tremendous efforts have been undertaken to increase the efficacy of 5-FU by investigating alternative schedules of delivery and biomodulation. However, bolus 5-FU in combination with folinic acid (FA), either as the Mayo Clinic or Roswell Park protocol, still represents the standard treatment for adjuvant and first-line palliative chemotherapy of colorectal cancer. In a recent meta-analysis, infusional protocols of 5-FU demonstrated increased response rates (14% to 22%) and a marginal, but significant survival benefit of 3 weeks (11.3 to 12.1 months). In view of the much higher costs and complicated management of infusional 5-FU regimens, this marginal survival benefit does not yet allow protracted 5-FU application to be defined as standard therapy. However, protracted 5-FU infusion in combination with radiation can be considered standard therapy as adjuvant treatment of rectal cancer, since it has demonstrated a significant increase in survival. In the future, oral 5-FU prodrugs may be substituted for infusional 5-FU. Furthermore, current data indicate that 5-FU will also be an essential component of combination chemotherapy protocols with the new active agents oxaliplatin, irinotecan, and raltitrexed. Preclinical studies show synergistic antitumor activity of 5-FU with these agents, which corresponds well with clinical response rates of 50% in untreated and 15% to 25% in 5-FU-refractory patients. Moreover, 5-FU-based pro-drug-active drug systems serve as excellent models for tumor-targeted gene therapy.

Phase II trial of trimetrexate for patients with advanced gastric carcinoma: an Eastern Cooperative Oncology Group study (E1287).

BACKGROUND: A Phase II study was conducted to evaluate the response, duration of response, and duration of survival of patients with measurable gastric carcinoma treated with trimetrexate (TMTX) who had not had prior chemotherapy. METHODS: Thirty-three patients with unresectable or metastatic gastric adenocarcinoma who had not received previous chemotherapy were treated with intravenous TMTX 12 mg/m(2) daily for 5 days. The dosage of TMTX was reduced to 8 mg/m(2) daily for 5 days for those who had received prior radiotherapy. The cycle was repeated every 3 weeks until disease progression or unacceptable toxicity occurred. RESULTS: Thirty-three patients could be analyzed with follow-up data. There was one Grade 5 (lethal) toxicity and four Grade 4 toxicities. Hematologic toxicity was the most common. The overall response rate was 21%, the overall median progression free survival was 2.7 months, and the overall median survival was 5.9 months for the entire cohort. No patients were alive at last follow-up. CONCLUSIONS: Though TMTX as a single agent has activity in gastric carcinoma with manageable toxicity, it cannot be recommended for routine use as a single agent due to the brief duration of response and median survival.

Selectivity in human breast cancer and human bone marrow using trimetrexate in combination with 5-fluorouracil.

The growth inhibitory effect of trimetrexate (TMQ) is maintained in MCF-7 breast cancer but is decreased in Hs 824.T human bone marrow cells by a priming- and non-toxic 5-fluorouracil (5-FU) dose. Incubation of MCF-7 breast cells with 10 microM TMQ alone or in combination with 10 M 5-FU (TMQ 2 h prior to 5-FU [TMQ/5-FU] or 5-FU 2 h prior to TMQ[5-FU/TMQ]) resulted in similar inhibitory effects but dissimilar effects occurred in Hs 824.T bone marrow. In breast cancer, the percentage differences among TMQ and TMQ/5-FU, TMQ and 5-FU/TMQ, and TMQ/5-FU and 5-FU/TMQ on growth rates, respectively, were 3.56%, 2.35%, and 1.68%. The percentage differences on growth rates of TMQ and TMQ/5-FU, TMQ and 5-FU/TMQ, and TMQ/5-FU and 5-FU/TMQ in bone marrow, respectively, were 5.76%, 30.03% (significant protection by 5-FU, i.e. the inhibitory effect of 5-FU/TMQ < or = TMQ), and 35.78% (sequence dependent). The growth rates of breast cancer and bone marrow cells in the presence of 5-FU were 96.03 +/- 1.17% and 94.59 +/- 1.15%, respectively, of control rates. These studies suggest that (a) TMQ and 5-FU combinations on the growth of MCF-7 breast cancer cells are independent of sequence of administration and best related to TMQ and (b) a priming- and non-toxic 5-FU dose protects against TMQ toxicity in human bone marrow while not affecting the maximum inhibitory effect of TMQ in breast cancer.

Therapeutic options for the treatment of colorectal cancer following 5-fluorouracil failure.

Therapeutic options after failure of 5-fluorouracil (5-FU) for the treatment of colorectal cancer include regional treatments, different 5-FU-based regimens, and different chemotherapy regimens. Of the regional treatments, resection of hepatic metastases is the most satisfactory because of the potential for long-term survival; however, the number of candidates for this option is limited. Responses are possible if 5-FU is administered by prolonged infusion, but the addition of other chemotherapeutic agents (eg, nitrosoureas, mitomycin C, or cisplatin) is less likely to induce objective responses. The new topoisomerase I inhibitor irinotecan has promising activity in patients with metastatic colorectal cancer. Depending on the status of the patient population, objective response rates of 15% to 30% have been reported in patients with colorectal cancer that has progressed or rapidly recurred following 5-FU-based treatment.

Biomodulation of Fluorouracil in colorectal cancer.

5-Fluorouracil (5-FU) remains the agent of choice for the treatment of colorectal cancer. Research has focused on the biomodulation of 5-FU in order to attempt to improve the cytotoxity and therapeutic effectiveness of this drug in the treatment of advanced colorectal cancer. Modulation of 5-FU by methotrexate (MTX), trimetrexate (TMTX), interferon-alpha (IFN-alpha), leucovorin (LV), or N-(phosphonacetyl)-L-asparte acid (PALA) has produced higher response rates than those observed with 5-FU alone. Methotrexate may improve the durability of response to or survival with 5-FU, but with inferior results compared with those in trials of 5-FU and leucovorin. Trimetrexate produces a number of responses, and further phase III trials are in progress to confirm the results of promising phase II trials with this drug. IFN-alpha has shown therapeutic efficiency when combined with 5-FU alone or with 5-FU and leucovorin, but latest studies with these combinations have shown increased toxicity. Initial single-institution phase I trials with 5-FU and PALA reported promising responses, but the latter responses with PALA were not substantiated in randomized multicenter trials. Leucovorin enhances the cytotoxic activity of 5-FU in vitro and in vivo, and several clinical trials have shown improved response rates and possible trends in improved survival when such therapy is compared with the use of 5-FU as a single-agent. More recent randomized trials have focused their attention on determining the optimal dose and schedule with this combination for producing a better clinical response with minimal toxicity. Schedules using infusional 5-FU appear to be the most active regimens when 5-FU is used as a single agent, as demonstrated by recent randomized trials. The Southwest Oncology Group (SWOG) and the Eastern Cooperative Oncology Group (ECOG) have performed separate randomized trials and have shown that the optimal regimens employ infusional 5-FU as a single agent, and that these are the least toxic regimens, perhaps more effective, and associated with a better quality of life. Future studies will focus on infusional regimens involving either short-term, high-dose protracted or long-term, low-dose protracted infusion of 5-FU, since these regimens have shown the most favorable toxicity spectrum and produced the longest survival times. Future research will also focus on the evaluation of various methods of delivery of 5-FU, including oral administration of the drug in combination with compounds that can modify its catabolism.

A randomized phase II trial of echinomycin, trimetrexate, and cisplatin plus etoposide in patients with metastatic nonsmall cell lung carcinoma: an Eastern Cooperative Oncology Group Study (E1587).

BACKGROUND: Patients with metastatic nonsmall cell lung carcinoma (NSCLC) usually have a poor prognosis. A chemotherapy regimen containing cisplatin is commonly used for symptom palliation. Echinomycin is a potent bifunctional intercalator of double-strand DNA; trimetrexate is a new derivative of methotrexate and is active against methotrexate-resistant tumor cells in vitro. METHODS: The Eastern Cooperative Oncology Group conducted a randomized Phase II study. Eligible patients were assigned to receive echinomycin 1200 microg/m2 by intravenous (i.v.) infusion over 30-60 minutes once a week for 4 weeks, repeated every 6 weeks; trimetrexate 12 mg/m2 i.v. bolus on Days 1-5 every 3 weeks, or 8 mg/m2 i.v. bolus on Days 1-5 for patients who had prior radiation to greater than 30% of their bone marrow; or cisplatin 60 mg/m2 i.v. on Day 1 and etoposide 120 mg/m2 i.v. on Days 1-3 every 4 weeks. Patients were evaluated before each cycle for tumor response, toxicity, and quality-of-life measurements. RESULTS: One hundred thirty-six patients were entered on the study, and 118 were evaluable for toxicity and response. The response rates were 16%, 5%, and 5% in patients treated with cisplatin and etoposide, echinomycin, and trimetrexate, respectively. There were no complete responses. The median survival was 37.9, 24.3, and 28.0 weeks for patients who received cisplatin and etoposide, echinomycin, and trimetrexate, respectively. Although cisplatin and etoposide appeared to give better therapeutic results, the response rate or survival did not reach statistical significance. This may have been due to inadequate sample size. Neither did quality-of-life measurement show any significant differences among treatments. CONCLUSIONS: Echinomycin and trimetrexate had minimal antitumor activity in patients with metastatic NSCLC: Response rate and survival remained poor in all three treatment arms. Patients should be encouraged to participate in clinical trials so that more effective therapy can be identified.